The present invention is directed to glassware forming systems that form articles of glassware from individual molten glass gobs, and more particularly to a method and apparatus for monitoring diameter of the molten glass gobs as they are fed to the forming system.
The art of manufacturing articles of glassware, such as glass containers, is currently served by the so-called individual section machine. Such a machine includes a plurality of separate or individual manufacturing sections, each of which has a multiplicity of operating mechanisms for converting one or more charges or gobs of molten glass into articles of glassware such as hollow glass containers, and for transferring the containers through successive stages of the machine section. In general, an individual section glassware forming machine system includes a glass source with a needle mechanism for controlling a stream of molten glass, a shear mechanism for cutting the molten glass into individual gobs, and a gob distributor for distributing the individual gobs among the individual machine sections. Each machine section includes one or more blank molds to which the molten glass gobs are fed through a loading funnel as illustrated in U.S. Pat. No. 5,917,106, and in which each glass gob is initially formed in a blowing or pressing operation. One or more invert arms transfer the blanks to blow molds in which the articles are blown to final form, tongs remove the formed articles onto a deadplate, and a sweepout mechanism transfers molded glass articles from the deadplate onto a machine conveyor. The conveyor receives containers from all sections of the individual section machine, and conveys the containers to a loader for transfer to an annealing lehr. Operating mechanisms in each section also provide for closure of mold halves, movement of baffles and blow nozzles, control of cooling wind, etc. U.S. Pat. No. 4,362,544 includes a background discussion of the art of both xe2x80x9cblow and blowxe2x80x9d and xe2x80x9cpress and blowxe2x80x9d glassware forming processes, and also discusses an electropneumatic individual section machine adapted for use in either process.
During operation of an individual section machine glassware forming system of this type, such factors as wear and erosion of the glass feed orifice at the molten glass source, or increase in glass forehearth temperature, can cause an increase in diameter of the molten glass gobs being fed to the blank molds of the individual machine sections. An increase in gob diameter can cause plugging or blocking of one or more blank loading funnels, necessitating shut-down and repair of at least one section of the glassware forming machine. It is an object of the present invention to provide a method and apparatus for monitoring the diameter of the molten glass gobs, and specifically for indicating an increase in molten glass gob diameter to a point at which there is a risk of blockage of the blank mold loading funnels.
A glassware manufacturing system in accordance with a presently preferred embodiment of the invention includes at least one blank mold, means such as a funnel for feeding gobs of molten glass in sequence to the blank mold, and means for monitoring diameter of the molten glass gobs. A temperature sensor is operatively coupled to the feeding means for providing an electrical signal indicative of temperature at the feeding means due to heat imparted thereto by the molten glass gobs, and means are responsive to the electrical signal for determining diameter of the molten glass gobs traveling through the feeding means. In the preferred apparatus of the invention, in which the feeding means includes a loading funnel for feeding molten glass gobs into each blank mold, the temperature sensor is operatively coupled to the funnel, and specifically to the outside surface of the funnel, for providing a measure of temperature at the outside funnel surface due to heat transfer through the funnel from molten glass gobs falling through the inside of the funnel. A change in the sensor signal, particularly an increase in the sensor signal, is interpreted as indicating an increase in gob diameter and potential blockage of the funnel.
In an individual section glassware forming machine in accordance with another aspect of the invention, each machine section has at least one blank mold, a loading funnel for feeding molten glass gobs into the blank mold, and a temperature sensor operatively coupled to an external surface of the funnel for providing an indication of temperature at the external surface by heat transfer through the funnel from molten glass gobs traveling through the funnel. Electronics are responsive to the sensor for indicating an increase in gob diameter as a function of an increase in temperature at the funnel external surface. In the preferred embodiment, the temperature at the sensor is compared with a preset or predetermined threshold, and an excessive gob diameter is indicated when funnel external surface temperature exceeds such threshold.
A method of monitoring diameter of molten glass gobs fed in sequence through a funnel to a blank mold of a glassware forming machine in accordance with a third aspect of the invention includes the steps of monitoring heat transfer from the molten glass gobs to the loading funnel and indicating an increase in gob diameter as a function of an increase in temperature at the funnel. Heat transfer to the funnel is monitored by operatively coupling a temperature sensor to the external surface of the funnel for monitoring heat transfer through the funnel from the glass gobs. An increase in gob diameter is indicated by comparing temperature of the funnel external surface to a predetermined threshold.
The invention, together with additional objects, features and advantages thereof, will be best understood from the following description, the appended claims and the accompanying drawing, which is a functional block diagram of an individual section glassware forming system in accordance with a presently preferred embodiment of the invention.